Relief-valve



T. A. CROMPTGN, J'R. REUF VALVE.

APPLICATION FILED DEC- 4, 1919.

UNITED sTArss PATENT OFFICE.-

RELIEF-VALVE. y

Specification of Letters Patent.

Patented Mar. 15, 1921.

I. Application led December 4, 1919. Serial-No. 342,447.

To all whom it may com/'erna Be it known that l, THOMAS ALBERT CROMPTON, Junior, a subject of the King of England, residing in Limehouse, London, E., England, have invented certain new and useful improvements in Relief-Valves, of which the following is a specification.

This invention is for improvements in or relating to relief-valves and has for its object to provide an improved construction of double-acting valve for use with containers of volatile substances such as petrol, so that the valve' may operate both as a vent to allow the escape of gas when the pressure in the container rises, and also to admit air when the pressure in the container is lowered.

Containers for such liquids .are frequently of very li ht construction so that it is essential that t ey should not be subjected to any great external pressure, whereas they are capable of withstandin a greater internal reassure, and it is the o ject of the present invention to provide a double-acting valve which shall operate to permit the entry of air to the container under a smaller pressure dierence than is permissible in the case ofthe excess pressure being in the interior of the container. Tn other words, the valve is to operate to admit air into thel container when the internal pressure is, say, one ounce per square inch less than atmosphere, but

when the pressure inside the container is in.

excess of atmospheric pressure, the valve does not operate -to release the pressure until such excess is, say, four ounces per square inch.

These gures are, of course, given by way of' example only.

According to this invention, a double-acting relief-valve adapted to operate in one direction under a smaller pressure diiference than that which is necessary to operate it in the other direction, comprises a liquid seal whereof the exposed surfaces of the liquid in the two limbs are unequal in area.

'The accompanying drawing which illus-` trates yone embodiment of this invention is an elevation partly in section and partly broken away to show the internal parts of the device. y

Referring to this drawing, the valve-body comprises a conduit 10 adapted to'be mounted vertically ona container to'be vented. lt may be provided with a screw-thread 11 at the lower end, and with a ange 12 whereby it may be connected alternatively to a pipe or direct to the container.l Qn the outside of the lwall 13 of the conduit 10 there .is formed an annular chamber 1d whereof the outer wall 15 extends upward above the upper end ofthe conduitI 10. This annular chamber contains a non-volatile liquid 16, suitable liquids being mercury, glycerin, or other material which shall not be deleteriously adected by the ases or vapors in the 'container to be vente A frame or cage 17 is secured to or formed integrally with the-upper end of the conduit 10 and it is provided with perforations 18. The upper end of the frame 17-terminates inla screwed spindle 19 formed at its lower end with an upwardly directed shoulder 20.

A -dome or bell 21 is formed with a suitable boss 22 at its apex and this boss is bored and threaded to fit on the spindle 19 yso that theI dome can be screwed onto the spindle. Thin washers 23 or other suitable packing material may be provided on 'theshoulder 20 to permit adjustment of the height of the bell 21 which is secured by a locknut 27. The lower edge 24 of the bell is so positioned that 'it is immersed in the liquid 16 to constitute the liquid seal, and the depth of immersion is adjusted by means of the aforesaid washers The special feature of the invention is that the bell is of such dimensions relatively to the diameters of the annular chamber that its lower edge is nearer one wall thereof than the other, so that the area of the liquid inside the bell is not e ual to the area of the liquid outside the bel ln the case illustrated, the exposed area inside is greater than the exposed area outside.

The bell is conveniently provided 'with a downwardly sloping flange 25, in its interior, near the surface of the liquid to pre` vent loss of liquid by surging or splashing, and an outwardly-directed {lange-26 ispre erably provided at the topof the conduit 10 lent` device, whichprevents the passage of flame therethrough but permits the free pasto coperate with 'the flange 25 for the same dealing with inflammable vapors, it

sage of air or vapor. This cover 30 may be provided with a downwardly .sloping flange 32 on its inner face to assist in preventing loss of liquid by splashing or surging.

Relief-valves of this type are usually used inthe open air and are therefore exposed to rain, and in the case of installations on board ship they may also be exposed to foam and spray. A drip-proof cover 40 is therefore providedy to protect the whole device. This cover Ll() is provided with openings 41 which are directed only downward so that rain or spray cannot enter. Conveniently this cover 40 is screwed on to the upper part of the wall 15 as at 42, and is provided with an inwardly-directed flange 43 whereby it grips and retains in place the abovementioned cover 30.

In the operation of this device, theinterior of the conduit 10, and of the bell 21, is in communication with the interior of the container or tank which is to be vented.y Assuming that the pressure in the tank rises, the liquid 50 inside the bell is forced out until its level is the same as that of the lower edge of the bell 21. liquid 50 is greater than the area 51 outside the bell, the difference of the levels inside and outside the bell lwill be considerable, for example as, indicated by the height L.

In the reverse operation, when the pressure in the tank falls below that of atmosphere, the liquid 51 is transferred to the interior of the bell at 50. Owing to the area of the liquid 50 being greater than that of the liquid 51, the level will rise by a smaller amount than in the previous Iinstance, say, for example as indicated at c. That is to say, the gases or vapor passing out from the 'tank have to do so against a head of liquid' h,

whereas air can pass into 'the tank against a smaller head of liquid as indicated by la. The ratio of the heights h and It' can be arranged to any predetermined value by suitably proportioning the areas of liquid exposed inside and outside the bell respectively..

The liquid selected for use will be one which is unaffected by the gases or vapors to whichit is subjected, and also according to the range of pressures over which the device isrequired to work. Where only very small pressure differences are required, a light liquid such as glycerin maybe used, whereas if larger pressures are required, a heavier liquid such as mercury may be found desirable in order to prevent the over-all dimensions of the device from becoming inconveniently large. These and other modifications as to the precise construction and arrangement of details are all held to lie within the scope of the present invention as set forth in the appended claims.

What I claim as my invention and desire to' secure b -Letters Patent is 1. A relief valve for containers compris- Since the area of the ing a conduit in communication with the interior of the container, a chamber in connection with the conduit, a bell extending down into said lchamber and dividing the same into unequal parts, the large part being next the conduit while the smallerpart is exposed to the atmosphere, and a liquid in lsaid chamber normally extending above the lower end of the bell on both sides, said liquid being raised through a lesser height on the inside of the bell-by atmospheric vpressure acting on the surface of the liquid column outside of the bell and being raised through a comparatively greater height on the outside of the bell by the pressure within the container before the atmospheric and container pres. sures respectively are. enabled to displace the seal formed by the liquid, substantially as described.

2. In a double-acting .relie'f-valve, ,.the combination of a verticallydis`posed conduit, an open frame vextending -colaxially upward from the upper end of said conduit, an annular chamber open at its up er side formed on said conduit a non-volati e liquid in said'chamber, a beil adjustably secured on said open frameV co-axially therewith extending downward with its o en end im mersed in the liquid and divi g the surface of said liquid into two unequal areas.

3. In a double-acting relief-valve, the combination of a vertically-disposed conduit, an open frame extending co-axially upward from the upper-end of said conduit, an annular chamber open at its upper side 100 formed on said conduit, va non-volatile liquid in said chamber, a bell adjustably secured on said open frame co-axially there# with exten'din downward with its open end immersed in t e liquid and dividing the sur- 105 face of said liquid intotwo une ual areas, a gauze cover inclosing the annu ar chamber and bell and permltting communicationA from the surface of the liquid outside the bell to atmos here. l

4. In a ouble-acting relief-valve, the` combination of a vertically-disposed conduit, an open frame extending co-axially upward from the upper end of said conduit, an annular chamber open at its upper side 115 formed on said conduit, a nonvolatile liquid in said chamber, a bell adjustably secured on said .open frame co-axially therewith ex' tending downward with its open'end immersed in the liquid and dividing the sur- 120 face of said li uid into two unequal areas, an outwardly- 'rected flange on the inner wall of the4 annular chamber, and an inwardly-directed flange on 'the inner surface of the bell cooperating with said outwardly- 125 directed flange to retain the said liquid in the said annular chamber.- i

5. In a double-actin relief-valve, the combination of a vertlcally-disposed conduit, an open frame extending co-axially up- 130 ward from the upper end of said conduit, a liquid dividing the surface of said liquid screw-threaded extension on said frame into two unequal areas, an upward extension formed with an upwardly-directed shoulder, of the outer wall of said annular chamber, spacing means on said shoulder, an annular a perforated cover secured on said wall and 5 chamber open at its upper Side formed on extending over said loell,l a metallic gauze- 15 said conduit, a non-volatile liquid in filling on the perorations of said cover, and said chamber, a bell perforated centrally, ,an outer drip-proof cover extending over threaded on said extension and resting on the whole device. said spacing means with its open end di- In testimony whereof I ailix my signature.

10 rected downward and immersed in said THOMAS ALBERT CROMPTON, Junior- 

